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Estrogen Containing Contraceptives

The current options for the combined estrogen and progesterone contraceptive methods are the oral pill, the transdermal patch or the vaginal ring (PPR). There are many non-contraceptive benefits of using a combined regimens, including but not limited to regulating menstrual cycles, treatment of menorrhagia/dysmenorrhea, improved bone mineral density, and the treatment of acne and pelvic pain (9).These regimens have also been shown to decrease the risk of endometrial, ovarian and colorectal cancers, and modern formulations have no increase in breast cancer risk.

As a class, there is an increased risk of venous thromboembolism (VTE) that is dependent on the estrogen dose and duration. Although the relative risk of VTE is increased, the absolute risk for each individual user is low, as thrombosis is a rare event in the healthy young female population that commonly use this contraceptive method. However, these combined regimens may also pose a high risk if patients are not carefully selected. (8)

For the malignant diagnosis’ specifically listed in the MEC, PPR are noted as a category 4 (unacceptable risk) for active cancer, current breast cancer, and malignant liver tumors. They are classified as a category 1 for gestational trophoblastic disease and ovarian cancer, and a category 2 for cervical cancer. It is important to take the overall medical condition into effect, as other conditions such obesity, hyperlipidemia, diabetes, liver and renal failure may be part of the medical history in chronically ill children. Similarly, it is important to note that any patient with a complicated solid organ transplant is not a candidate for estrogens (category 4), but an uncomplicated transplant is considered a category 2.

Pills:

Combined oral contraceptive pills (COCs) are available in a wide variety of formulations. The choice of pill should be determined by the patient and physician based on clinical picture, history and preference. The basic mechanism of action is the same and includes both inhibition of ovulation and folliculogenesis, and thickening of cervical mucus. As a class, all estrogen based contraceptives are tier 2 efficacy, with a typical use first year failure rate of nine percent. COCs are taken daily and depending on the cycling pattern chosen can be given between 21-90 days with a 4-7 days pill free interval for withdraw bleeding.

Patch:

A thin, flexible patch that contains 6 milligram of norelgestromin (active metabolite of norgestimate) and 0.75 mg of ethinyl estradiol (EE). The patch releases 150 micrograms of norelgestromin and 20 mcg of EE daily. The patch provides serum levels of EE that are higher than common 35 EE COC formulations; however the VTE risk of the patch is equivalent to a 35EE/norgestimate oral contraceptive pill. The patch is applied to the buttocks, upper arm, lower abdomen or upper torso and change once weekly for three weeks. The fourth week is a hormone free interval to allow for cycling. It’s mechanism of action is the same as that of the oral contraceptive pills. In some studies, the patch appears to enhance consistent and correct use as compared to COCs, however their continuation rates and failure rates are the same. Patch uses may note a transient skin reaction and more initial breakthrough bleeding than COCs users that decreases with use. Patients greater than 90 kilograms may have a higher risk of pregnancy when using the birth control patch. (8)

Ring:

A soft, transparent flexible ring that releases 120 mcg of etonogestrel (major metabolite of desogestrel) and 15 mcg of EE daily. Although several cases of VTE have been reported in vaginal ring users, the EE levels are 2 and 3 fold lower than that found in 35EE COCs and the birth control patch. However, there have been studies linking the progesterone component of the ring to an increased risk of VTE. Possibly due to the low estrogen output, studies have not shown improvement in bone mineral density using the ring, even after 24 months of use.The ring is placed vaginally once every 28 days – with the last 7 days being a ring free timeframe to allow for withdraw bleeding. The mechanism of action is mostly ovulation suppression, similar to oral contraceptive pills. In theory, the ease of once monthly use should improve patient compliance and improve method success rates. However, in randomized comparative trial the ring and COCs showed similarly high compliance rate and similarly poor continuation rates. The vaginal ring has excellent cycle control (even in the first few cycles). It can be removed for up to three hours without compromising effectiveness and is safe to use with tampons or during intercourse. The most commonly reported side effects are headache and vaginal wetness. (8)